Cybercriminals turn Microsoft Excel into their accessory with a new trick to attack users

Perpetrators go on inventing cunning techniques to attack users. One of the most popular tricks of infecting a computer is poisoned MS Office files with a malicious script inside. A new dangerous threat related to this kind of attack has newly appeared. Hackers use .IQY files to get a total remote access to a victim’s computer. And what makes the threat especially dangerous is that many antiviruses can’t detect it.

Here is an example of a phishing email used in such attack.

The email was used to spread FlawedAmmyy, a kind of Remote Administration Tool (RAT) attached to phishing emails. But in this case, the most interesting thing is not a phishing email itself. And not even the payload. Because as you will see a bit later, almost any malware can be used as a payload here. So the most intriguing thing is the process of infecting a computer.

Let’s look under the hood to understand how exactly it works.

Let’s begin with .IQY files.

.IQY files are intended for making an Internet query from MS Excel, so an .IQY contains a URL and other related parameters. It can download files and run them directly into MS Excel.

Just think about that: a couple strings of code can download and run on your machine anything form the Internet. Of course, malicious hackers couldn’t pass by such impressive possibility for committing cybercrimes.

If we run the file, it will be opened with Excel in accompany with the security notice about blocking the process. To continue, we need to permit it by clicking the “Enable” button. That’s how MS Office is configured by default for security reasons.

But can it be considered reliable protection? Obviously, no. And here’s why.

Not surprisingly, most security-reckless users just click “Enable” even without thinking. But much more shockingly, many techy-educated people do even worse. They deliberately change security setting to enable all data connections without a permission. Why? Just for not seeing this “annoying warning popups”.

They do it in the Excel’s settings:

Excel Home ->Excel Options->Trust Center settings -> External Content

And that’s not all. Cybercriminals can covertly change the default “DataConnectionWarnings” option in the Registry settings using a malware to overwrite its value from 1 to 0.

HKEY_CURRENT_USERSOFTWAREMicrosoftOfficeExcelSecurity

If the “warnings “parameter is on, a user sees this popup when trying to run an .IQY file.

But if it’s disabled, the warning won’t appear.

Now let’s click “Enable” and see what’s happening next.

Here is the code executed.

As you can see, 14459.iqy execution invokes content of “2.dat” file that downloads the file named “1.dat”.

Finally, let’s look at the content of the file “1.dat”.

The file doc.xls you can see in the malicious link in reality is a binary malware. Downloaded by this malicious script, it runs PowerShell.

And then, having PowerShell under control, it can download and execute any malicious application in any desired location. Also, as the malware uses legitimate Microsoft tools to infect computers, it makes pretty much harder for antiviruses to detect the attack.

Let’s repeat it again: almost any malicious file can be spread by this pattern. Thus it’s absolutely unpredictable what kind of malware it will bring next time. So you need to build the protection to neutralize not a special malware but the infecting pattern itself.

How can you do that?

Never set “Enable all data connections” by default or disable warning functions in MS Office and System Registry

Never run files from unknown sources

Use reliable and up-to-date antimalware solutions

Use exclusive Comodo auto-containment technology that allows you to open an uncertain file in the isolated environment, so it can’t do any harm to your computer.

Comodo Cybersecurity is a global innovator of cybersecurity solutions, and a division of Comodo Security Solutions Inc. For over 20 years, Comodo Cybersecurity has been at the forefront of successfully protecting the most sensitive data; and today, we deliver an innovative cybersecurity platform that renders threats useless across the LAN, Web & Cloud.
Comodo Cybersecurity’s ongoing mission is to protect what matters most, while enabling businesses and customers to confidently accept risk in a world where preventing all attacks is impossible.

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